(Reuters) - Playboy founder Hugh Hefner, who helped usher in the 1960s sexual revolution with his groundbreaking men’s magazine and built a business empire around his libertine lifestyle, died on Wednesday at the age of 91, Playboy Enterprises said.

Hefner, once called the “prophet of pop hedonism” by Time magazine, peacefully passed away at his home, Playboy Enterprises said in a statement.

Hefner was sometimes characterized as an oversexed Peter Pan as he kept a harem of young blondes that numbered as many as seven at his legendary Playboy Mansion. This was chronicled in “The Girls Next Door,” a TV reality show that aired from 2005 through 2010. He said that thanks to the impotency-fighting drug Viagra he continued exercising his libido into his 80s.

“I‘m never going to grow up,” Hefner said in a CNN interview when he was 82. “Staying young is what it is all about for me. Holding on to the boy and long ago I decided that age really didn’t matter and as long as the ladies ... feel the same way, that’s fine with me.”

Hefner settled down somewhat in 2012 at age 86 when he took Crystal Harris, who was 60 years younger, as his third wife.

He said his swinging lifestyle might have been a reaction to growing up in a repressed family where affection was rarely exhibited. His so-called stunted childhood led to a multi-million-dollar enterprise that centered on naked women but also espoused Hefner’s “Playboy philosophy” based on romance, style and the casting off of mainstream mores.

That philosophy came to life at the legendary parties in his mansions - first in his native Chicago, then in Los Angeles’ exclusive Holmby Hills neighborhood - where legions of male celebrities swarmed to mingle with beautiful young women.

Long before the Internet made nudity ubiquitous, Hefner faced obscenity charges in 1963 for publishing and circulating photos of disrobed celebrities and aspiring stars but he was acquitted.

Hefner created Playboy as the first stylish glossy men’s magazine and in addition to nude fold-outs, it had intellectual appeal with top writers such as Kurt Vonnegut, Joyce Carol Oates, Vladimir Nabokov, James Baldwin and Alex Haley for men who liked to say they did not buy the magazine just for the pictures.

In-depth interviews with historic figures such as Fidel Castro, Martin Luther King Jr., Malcolm X and John Lennon also were featured regularly.

“I’ve never thought of Playboy quite frankly as a sex magazine,” Hefner told CNN in 2002. “I always thought of it as a lifestyle magazine in which sex was one important ingredient.”

Hefner proved to be a genius at branding. The magazine’s rabbit silhouette became one of the best known logos in the world and the “bunny” waitresses in his Playboy nightclubs were instantly recognizable in their low-cut bathing suit-style uniforms with bow ties, puffy cotton tails and pert rabbit ears.

Hef, as he began calling himself in high school, also was a living logo for Playboy, presiding over his realm in silk pajamas and a smoking jacket while puffing on a pipe.

After writing copy for Esquire magazine, Hefner married and worked in the circulation department of Children’s Activities magazine when he began plotting what would become Playboy magazine.

The first issue came out in December 1953 - featuring nude photos of actress Marilyn Monroe - and was a hit. As the magazine took off, it was attacked from the right because of the nudity and from the left by feminists who said it reduced women to sex objects.

Hefner once declared sex to be “the primary motivating factor in the course of human history” and, using that as a business model Playboy flourished during the sexual revolution and into the 1970s with monthly circulation hitting 7 million.

He ran into trouble in the 1980s with competition from Penthouse and Hustler - magazines that had much more explicit photos - and Playboy’s social impact faded considerably by the 21st century. The Playboy Clubs closed in 1991 but would be partially revived.

After suffering a minor stroke in 1985, Hefner made daughter Christie chief executive officer of Playboy Enterprises and she gave the business a makeover before stepping down in 2009. Hefner’s son, Cooper, who was nearly 40 years younger than Christie, assumed a major role in the company in 2014.

“My father lived an exceptional and impactful life as a media and cultural pioneer and a leading voice behind some of the most significant social and cultural movements of our time in advocating free speech, civil rights and sexual freedom,” Cooper said in a statement, according to posts on social media.

Playboy magazine, starting with its March 2016 issue, did away with full frontal nudity in a rebranding that would have been unimaginable in the publication’s heyday.

Playboy resumed nudity a year later as Hefner’s son Cooper announced a new philosophy for the company.

In August 2016, one of Hefner’s neighbors, a private equity investor, announced he had bought the Playboy mansion for $100 million with the understanding Hefner could stay there until he died.

Before Playboy, Hefner married Millie Williams in 1949 and they divorced in 1959, starting a period in which he became the ultimate bachelor. The many women who shared his round, motorized, vibrating bed included models who posed in his magazine and in 1989 he married one of them, Playmate of the Year Kimberly Conrad.

They had two sons but Hefner’s experiment with traditional domesticity ended in divorce after 10 years. Conrad moved into a home next to Hefner so he could stay close to their sons.

In 2008 after one of his girlfriends, Holly Madison, broke up with Hefner, he said he had hoped to spend the rest of his life with her. Shortly afterward he added 19-year-old twins to his group before turning to marriage again with Harris.

Reporting by Subrat Patnaik in Bengaluru,; Brendan O'Brien in Milwaukee and Alex Dobuzinskis in Los Angeles; Editing by Gopakumar Warrier and Michael Perry